invasive

from The American Heritage® Dictionary of the English Language, 5th Edition.

• adjective Of, engaging in, or given to armed aggression.
• adjective Of or relating to a disease or condition that has a tendency to spread, especially into healthy tissue.
• adjective Of or relating to a medical procedure in which a part of the body is entered, as by puncture or incision.
• adjective Tending to spread widely in a habitat or ecosystem. Used especially of nonnative species.
• adjective Tending to intrude or encroach, as upon privacy.
• noun An invasive species or organism.

from The Century Dictionary.

• Tending to invade; characterized by invasion; aggressive.

from the GNU version of the Collaborative International Dictionary of English.

• adjective Tending to invade; characterized by invasion; aggressive.
• adjective (Med.) tending to spread, especially tending to intrude into healthy tissue; -- used mostly of tumors.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective that invades a foreign country using military force
• adjective of a plant or animal that invades a habitat to the detriment of native species
• adjective medicine (of a carcinoma etc) that invades healthy tissue; (of a procedure) in which part of the body is entered
• adjective intruding on one's privacy, or trespassing
• noun An invasive organism, as, a plant or animal.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• adjective marked by a tendency to spread especially into healthy tissue
• adjective gradually intrusive without right or permission
• adjective involving invasion or aggressive attack
• adjective relating to a technique in which the body is entered by puncture or incision